Identification Of Heavy Metal Transporters

Abstract

Increased release of heavy metals of geogenic and anthropogenic origin has led to generation of multiple polluted sites in the USA and across the world that are waiting for efficient clean-up technologies. Phytoremediation uses plants to mitigate these types of environmental problems, and provides a cost-efficient and environmentally friendly alternative to existing remediation solutions. Application of phytoremediation relies on the understanding of mechanisms of heavy metal detoxification in plants. As one of the most important heavy metal detoxification mechanisms, the phytochelatin dependent pathway plays an essential role in detoxification and sequestration of heavy metals in plants, fungi and some nematodes. While the mechanism of phytochelatin biosynthesis has been well established, proteins mediating transport of phytochelatins and/or heavy metal phytochelatin complexes have eluded definition. My PhD research led to the following findings: firstly, it was found that Arabidopsis Oligopeptide Transporter 3 (OPT3) mediates transport of cadmium and contributes to shoot accumulation of glutathione and phytochelatins. Secondly, in collaboration with three other research groups, it was shown that an ATPbinding cassette transporter of Schizosaccharomyces pombe, Abc2, is the long-sought phytochelatin transporter on the vacuolar membrane. Identification of such transporter(s) greatly improves the understanding of heavy metal detoxification mechanisms and provides promising bioengineering target(s) for phytoremediation applications. Thirdly, an efficient reverse genetic method was developed to study the function of genes of interest through RNA interference in plant protoplasts. The protocol has been developed for Arabidopsis thaliana; however, since protoplasts can be isolated from different tissues and different plant species, direct transfer of synthetic double stranded RNA into protoplasts can be employed as a gene-silencing tool to study tissue specific processes in a variety of species, and can be adapted to a high-throughput format.